Method and composition for washing poultry during processing

ABSTRACT

The present invention relates to compositions including peroxyacetic acid and peroxyoctanoic acid and methods for reducing microbial contamination on poultry. The methods include the step of applying a mixed peroxycarboxylic acid composition to poultry.

FIELD OF THE INVENTION

The present invention relates to compositions including peroxyaceticacid and peroxyoctanoic acid and methods for reducing microbialcontamination on poultry. The methods include the step of applying amixed peroxycarboxylic acid composition to poultry.

BACKGROUND OF THE INVENTION

All poultry carcasses entering the processing environment arecontaminated with bacteria, some with pathogenic bacteria such asSalmonella. Fecal matter and dirt are the main sources of thiscontamination. As a result of such contamination, poultry is typicallywashed at any of several steps during the process of converting a livebird to an edible food product. Such washing aims to remove dirt, offal,blood, viscera, other debris, and microbes from the poultry. Removing orreducing microbes aids the safe storage and consumption of poultry, yetmany existing washing procedures fail to significantly reduce themicrobe burden on poultry. The potential for poultry skin to becomecross-contaminated is worsened by the ability of all types of bacteria(Gram-positive, Gram-negative, flagellated, non-flagellated, rods orcocci) to adhere within only 15 seconds of contact. Once in theprocessing environment, a significant number of carcasses can becomecross-contaminated with pathogens during handling, scalding, mechanicalprocessing, and chilling. Current methods for many of these proceduresalso fail to significantly reduce the microbe burden on poultry.

Water used for washing or these other procedures is often usedrepeatedly over time, which provides yet another opportunity spreading,rather than reducing, microbial burden on poultry. For example, thewater becomes contaminated with organic matter and microbes from thepoultry, and the organic matter provides nutrients for microbial growthin the water over time or through additional use. These microbes cangrow on and contaminate additional poultry and processing equipment. Inparticular, water left untreated in a submersion bath tends todecontaminate poultry early in a shift but contaminates poultry later inthe shift. In fact, such water has been identified as a potential sourceof coliform, E. coli and Salmonella contamination or cross contaminationduring poultry processing. Salmonella and other microorganisms aregenerally undesirable to the poultry, the water, and can cause buildupon all water contact surfaces of slime or biofilm, which requiresfrequent cleaning to remove.

Microbial contamination or cross contamination of poultry via watercontinues to be a major concern for poultry processors and end users.Although washing, cooling, or heating poultry carcasses with water canreduce potential contamination, the processing water can also serve as asource of contamination or cross contamination. If pathogenicmicroorganisms in water are not removed, inactivated or otherwisecontrolled, they can spread to other poultry, potentially contaminatingthem. Further, handling or processing steps that pool many individualpoultry parts tend to increase the risk that a single contaminated itemmay contaminate the entire lot. Immersing or spray-washing poultry infresh water can help reduce surface populations of microorganisms.However sterilization by repeated washing, even with sterile water,cannot be achieved because microorganisms within tissues of poultryremain in place.

The addition of antimicrobial agents to wash or process water caninactivate vegetative bacteria cells in water, helping avoidcontamination. Ideally, an antimicrobial agent or compound used in sucha system will have several important properties in addition to itsantimicrobial efficacy. The compound or agent should have no technicaleffect on the final food product. Residual activity implies the presenceof a film of antimicrobial material which will continue to haveantimicrobial effect which may require further rinsing of the foodproduct. The antimicrobial agent preferably should also be odor free toprevent transfer of undesirable odors onto food stuffs. If direct foodcontact occurs, the antimicrobial agent should also be composed of foodadditive materials which will not affect food wholesomeness, nor affecthumans should incidental ingestion result. In addition, theantimicrobial agent should preferably be composed of naturally occurringor innocuous ingredients, which are chemically compatible with theenvironment and cause no concerns for toxic residues within the water.

In the past, poultry wash or process waters have generally been treatedwith chlorinated compounds, organic acids, acidified sodium chlorite,trisodium phosphate, or ozone. Generally, these materials are effectivein reducing microbial contamination on poultry. However, the use rate ofthese antimicrobials is very high because they are not effective at lowconcentrations or they tend to be rapidly consumed by the high organicload included with the poultry. Excessive chlorination of foodprocessing water with hypochlorite has prompted concern over productionof toxic or carcinogenic organochlorine compounds and other by-products.

Further, the efficacy of conventional antimicrobial agents on thesurface of poultry is often limited. For example, it has been reportedthat, generally, concentrations of more than 4 wt-% of organic acids orof 5 to 10 wt-% of trisodium phosphate are required to effectivelyreduce contamination of poultry skin by S. typhimurium. Antimicrobialagents such as peroxides or lactic acid can result in discoloring,bleaching, or bloating of poultry tissue.

The EPA approved a peroxyacetic acid-based composition in 1996 forcontrolling microbial growth and reducing biofilm formation in fruit andvegetable transport or process waters. From a historical perspective,peroxyacetic acid has been used for food contact surface sanitizing,aseptic packaging and medical device cold-sterilization. In addition toits biocidal properties, the environmentally-friendly decompositionbyproducts and good stability in the presence of organic matter helpedgain acceptance of this technology among fruit and vegetable packers,handlers, and processors.

Nevertheless, there remains a need for improved antimicrobialcompositions for addition to waters used for washing or processingpoultry.

SUMMARY OF THE INVENTION

The present invention relates to compositions including peroxyaceticacid and peroxyoctanoic acid and methods for reducing microbialcontamination on poultry. The methods include the step of applying amixed peroxycarboxylic acid composition to poultry. The compositions andmethods of the invention provide an antimicrobial agent useful in waterfor washing or processing poultry, that has a high degree ofantimicrobial efficacy, and that is safely ingestible by humans whileimposing no unacceptable environmental incompatibility.

A preferred antimicrobial composition of the present invention includesacetic acid, octanoic acid, peroxyacetic acid, peroxyoctanoic acid, andhydrogen peroxide. In one embodiment, an antimicrobial concentratecomposition of the present invention includes about 40 to about 70weight-% acetic acid, about 2 to about 20 weight-% octanoic acid, andabout 5 to about 15 weight-% hydrogen peroxide. In another embodiment,the antimicrobial concentrate composition of the present inventionincludes an equilibrium mixture resulting from a combination of about 40to about 70 weight-% acetic acid, about 2 to about 20 weight-% octanoicacid, and about 5 to about 15 weight-% hydrogen peroxide. In a thirdembodiment, the antimicrobial concentrate composition of the presentinvention includes about 30 to about 60 weight-% acetic acid, about 1 toabout 15 weight-% octanoic acid, about 2 to about 12 weight-% hydrogenperoxide, about 6 to about 16 weight-% peroxyacetic acid, and about 0.1to about 5 weight-% peroxyoctanoic acid.

In one embodiment, an antimicrobial use composition of the inventionincludes about 5 to about 1000 ppm acetic acid, about 0.5 to about 100ppm octanoic acid, about 1 to about 200 ppm hydrogen peroxide, about 2to about 300 ppm peroxyacetic acid, and about 0.1 to about 20 ppmperoxyoctanoic acid.

The compositions of the invention and other mixed peroxycarboxylic acidantimicrobial compositions can be employed in methods for reducingmicrobial contamination on poultry and in water used for washing orprocessing poultry. Preferred mixed peroxycarboxylic acid antimicrobialcompositions for use in the methods of the invention include mixtures ofperoxyacetic acid and peroxyoctanoic acid in either liquid or gaseousform. These methods include applying to the poultry during processing amixed peroxycarboxylic acid antimicrobial composition, preferably in anamount and time sufficient to reduce the microbial population. Thecomposition can be applied by methods including submersing, rinsing,spraying, or air chilling the poultry, or a combination of these routes.During processing, the composition can be applied to whole, dismembered,portioned, or boned poultry.

In one embodiment of the method of the invention, the method includesrecovering a mixed peroxycarboxylic acid antimicrobial compositionpreviously applied to poultry. The recovered composition can be treatedby adding a sufficient amount of a mixture of peroxycarboxylic acids toyield a recycled mixed peroxycarboxylic acid antimicrobial composition.The recycled mixed composition includes a reduced level of microbes,such as human pathogens, and can be disposed of more safely.Alternatively, the recycled mixed composition can be applied to poultryduring processing. Preferably, the mixture of peroxycarboxylic acidsadded to form the recycled composition is formed by adding a concentratecomposition of peroxyacetic acid and peroxyoctanoic acid to form acomposition with suitable use antimicrobial levels of theseperoxycarboxylic acids.

The compositions can include peroxyheptanoic and/or peroxynonanoic acidin place of or in addition to peroxyoctanoic acid.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

As used herein the term “poultry” refers to all forms of any bird kept,harvested, or domesticated for meat or eggs, and including chicken,turkey, ostrich, game hen, squab, guinea fowl, pheasant, quail, duck,goose, emu, or the like and the eggs of these birds. Poultry includeswhole, sectioned, processed, cooked or raw poultry, and encompasses allforms of poultry flesh, by-products, and side products. The flesh ofpoultry includes muscle, fat, organs, skin, bones and body fluids andlike components that form the animal. Forms of animal flesh include, forexample, the whole or part of animal flesh, alone or in combination withother ingredients. Typical forms include, for example, processed poultrymeat, such as cured poultry meat, sectioned and formed products, mincedproducts, finely chopped products and whole products.

As used herein, the terms “mixed” or “mixture” when used relating to“peroxycarboxylic acid composition” or “peroxycarboxylic acids” refer toa composition or mixture including more than one peroxycarboxylic acid,such as a composition or mixture including peroxyacetic acid andperoxyoctanoic acid.

As used herein, the phrase “poultry debris” refers to any debris,residue, material, dirt, offal, poultry part, poultry waste, poultryviscera, poultry organ, fragments or combinations of such materials, andthe like removed from a poultry carcass or portion during processing andthat enters a waste stream.

As used herein, the phrase “densified fluid” refers to a fluid in acritical, subcritical, near critical, or supercritical state. The fluidis generally a gas at standard conditions of one atmosphere pressure and0° C. As used herein, the phrase “supercritical fluid” refers to a densegas that is maintained above its critical temperature, the temperatureabove which it cannot be liquefied by pressure. Supercritical fluids aretypically less viscous and diffuse more readily than liquids. Preferablya densified fluid is at, above, or slightly below its critical point. Asused herein, the phrase “critical point” is the transition point atwhich the liquid and gaseous states of a substance merge into each otherand represents the combination of the critical temperature and criticalpressure for a substance. The critical pressure is a pressure justsufficient to cause the appearance of two phases at the criticaltemperature. Critical temperatures and pressures have been reported fornumerous organic and inorganic compounds and several elements.

As used herein, the terms “near critical” fluid or “subcritical” fluidrefer to a fluid material that is typically below the criticaltemperature of a supercritical fluid, but remains in a fluid state anddenser than a typical gas due to the effects of pressure on the fluid.Preferably a subcritical or near critical fluid is at a temperatureand/or pressure just below its critical point. For example, asubcritical or near critical fluid can be below its critical temperaturebut above its critical pressure, below its critical pressure but aboveits critical temperature, or below both its critical temperature andpressure. The terms near critical and subcritical do not refer tomaterials in their ordinary gaseous or liquid state.

As used herein, the term “about” modifying the quantity of an ingredientin the compositions of the invention or employed in the methods of theinvention refers to variation in the numerical quantity that can occur,for example, through typical measuring and liquid handling proceduresused for making concentrates or use solutions in the real world; throughinadvertent error in these procedures; through differences in themanufacture, source, or purity of the ingredients employed to make thecompositions or carry out the methods; and the like. The term about alsoencompasses amounts that differ due to different equilibrium conditionsfor a composition resulting from a particular initial mixture. Whetheror not modified by the term “about”, the claims include equivalents tothe quantities.

Differentiation of antimicrobial “-cidal” or “-static” activity, thedefinitions which describe the degree of efficacy, and the officiallaboratory protocols for measuring this efficacy are considerations forunderstanding the relevance of antimicrobial agents and compositions.Antimicrobial compositions can effect two kinds of microbial celldamage. The first is a lethal, irreversible action resulting in completemicrobial cell destruction or incapacitation. The second type of celldamage is reversible, such that if the organism is rendered free of theagent, it can again multiply. The former is termed microbiocidal and thelater, microbistatic. A sanitizer and a disinfectant are, by definition,agents which provide antimicrobial or microbiocidal activity. Incontrast, a preservative is generally described as an inhibitor ormicrobistatic composition.

For the purpose of this patent application, successful microbialreduction is achieved when the microbial populations are reduced by atleast about 50%, or by significantly more than is achieved by a washwith water. Larger reductions in microbial population provide greaterlevels of protection for processed poultry product.

As used herein, a composition or combination “consisting essentially” ofcertain ingredients refers to a composition including those ingredientsand lacking any ingredient that materially affects the basic and novelcharacteristics of the composition or method. The phrase “consistingessentially of” excludes from the claimed compositions and methods: acoupling agent; an ingredient that cannot be employed in food productsor in food wash, handling, or processing according to U.S. governmentrules or regulations; and/or a peroxycarboxylic acid or carboxylic acidwith 10 or more carbon atoms; unless such an ingredient is specificallylisted after the phrase.

Peroxycarboxylic Acid Antimicrobial Composition

Compositions of Carboxylic Acids and Peroxycarboxylic Acids

Among other constituents, the composition of the present inventionincludes a carboxylic acid. Generally, carboxylic acids have the formulaR—COOH wherein the R can represent any number of different groupsincluding aliphatic groups, alicyclic groups, aromatic groups,heterocyclic groups, all of which can be saturated or unsaturated aswell as substituted or unsubstituted. Carboxylic acids can have one,two, three, or more carboxyl groups. The composition and methods of theinvention can employ carboxylic acids containing as many as 18 carbonatoms. Examples of suitable carboxylic acids include formic, acetic,propionic, butanoic, pentanoic, hexanoic, heptanoic, octanoic, nonanoic,decanoic, undecanoic, dodecanoic, lactic, maleic, ascorbic, citric,hydroxyacetic, neopentanoic, neoheptanoic, neodecanoic, oxalic, malonic,succinic, glutaric, adipic, pimelic and subric acid. Carboxylic acidswhich are generally useful are those having one or two carboxyl groupswhere the R group is a primary alkyl chain having a length of C₂ to C₁₂.The primary alkyl chain is that carbon chain of the molecule having thegreatest length of carbon atoms and directly appending carboxylfunctional groups. Octanoic acid can reduce surface tension to assist inwetting of hydrophobic surfaces like poultry skin.

Peroxycarboxylic (or percarboxylic) acids generally have the formulaR(CO₃H)_(n), where R is an alkyl, arylalkyl, cycloalkyl, aromatic orheterocyclic group, and n is one, two, or three, and named by prefixingthe parent acid with peroxy. While peroxycarboxylic acids are not asstable as carboxylic acids, their stability generally increases withincreasing molecular weight. Thermal decomposition of these acids cangenerally proceed by free radical and nonradical paths, byphotodecomposition or radical-induced decomposition, or by the action ofmetal ions or complexes. Percarboxylic acids can be made by the direct,acid catalyzed equilibrium action of hydrogen peroxide with thecarboxylic acid, by autoxidation of aldehydes, or from acid chlorides,and hydrides, or carboxylic anhydrides with hydrogen or sodium peroxide.

Peroxycarboxylic acids useful in the compositions and methods of thepresent invention include peroxyformic, peroxyacetic, peroxypropionic,peroxybutanoic, peroxypentanoic, peroxyhexanoic, peroxyheptanoic,peroxyoctanoic, peroxynonanoic, peroxydecanoic, peroxyundecanoic,peroxydodecanoic, peroxylactic, peroxymaleic, peroxyascorbic,peroxyhydroxyacetic, peroxyoxalic, peroxymalonic, peroxysuccinic,peroxyglutaric, peroxyadipic, peroxypimelic and peroxysubric acid andmixtures thereof. Peroxy forms of carboxylic acids with more than onecarboxylate moiety can have one or more of the carboxyl moieties presentas peroxycarboxyl moieties. These peroxycarboxylic acids have been foundto provide good antimicrobial action with good stability in aqueousmixtures. In a preferred embodiment, the composition of the inventionutilizes a combination of several different peroxycarboxylic acids.Preferably, the composition includes one or more small C₂-C₄peroxycarboxylic acids and one or more large C₇-C₉ peroxycarboxylicacids. Especially preferred is an embodiment in which the smallperoxycarboxylic acid is peroxyacetic acid and the large acid isperoxyoctanoic acid.

Typically, the compositions and methods of the present invention includeperoxyacetic acid. Peroxyacetic (or peracetic) acid is aperoxycarboxylic acid having the formula: CH₃COOOH. Generally,peroxyacetic acid is a liquid having an acrid odor at higherconcentrations and is freely soluble in water, alcohol, ether, andsulfuric acid. Peroxyacetic acid can be prepared through any number ofmethods known to those of skill in the art including preparation fromacetaldehyde and oxygen in the presence of cobalt acetate. A solution ofperoxyacetic acid can be obtained by combining acetic acid with hydrogenperoxide. A 50% solution of peroxyacetic acid can be obtained bycombining acetic anhydride, hydrogen peroxide and sulfuric acid. Othermethods of formulation of peroxyacetic acid include those disclosed inU.S. Pat. No. 2,833,813, which is incorporated herein by reference.

Typically, the compositions and methods of the present invention includeperoxyoctanoic acid, peroxynonanoic acid, or peroxyheptanoic acid,preferably peroxyoctanoic acid. Peroxyoctanoic (or peroctanoic) acid isa peroxycarboxylic acid having the formula, for example, ofn-peroxyoctanoic acid: CH₃(CH₂)₆COOOH. Peroxyoctanoic acid can be anacid with a straight chain alkyl moiety, an acid with a branched alkylmoiety, or a mixture thereof. Peroxyoctanoic acid can be preparedthrough any number of methods known to those of skill in the art. Asolution of peroxyoctanoic acid can be obtained by combining octanoicacid and hydrogen peroxide.

A preferred antimicrobial composition of the present invention includesacetic acid, octanoic acid, peroxyacetic acid, and peroxyoctanoic acid.Such a composition can also include a chelating agent. A preferredcomposition preferably includes a combination of peroxyacetic acid andperoxyoctanoic acid effective for killing one or more of the food-bornepathogenic bacteria associated with poultry, such as Salmonellatyphimurium, Campylobacter jejuni, Listeria monocytogenes, andEscherichia coli O157:H7, and the like. The compositions and methods ofthe present invention have activity against a wide variety ofmicroorganisms such as Gram positive (for example, Listeriamonocytogenes) and Gram negative (for example, Escherichia coli)bacteria, yeast, molds, bacterial spores, viruses, etc. The compositionsand methods of the present invention, as described above, have activityagainst a wide variety of human pathogens. The compositions and methodscan kill a wide variety of microbes on the surface of a poultry or inwater used for washing or processing of poultry.

The preferred compositions include concentrate compositions and usecompositions. Typically, an antimicrobial concentrate composition can bediluted, for example with water, to form an antimicrobial usecomposition. In a preferred embodiment, the concentrate composition isdiluted into water employed for washing or processing poultry.

Liquid Peroxycarboxylic Acid Antimicrobial Composition

A preferred antimicrobial concentrate composition of the presentinvention includes about 40 to about 70 weight-%, preferably about 45 toabout 65 weight-%, preferably about 50 to about 60 weight-% acetic acid;about 2 to about 20 weight-%, preferably about 2 to about 8 weight-%octanoic acid; and about 5 to about 15 weight-% hydrogen peroxide. Thiscomposition can advantageously also include about 0.3 to about 1weight-% chelating agent. Preferably, such an antimicrobial concentratecomposition includes about 55 weight-% acetic acid, about 11 weight-%hydrogen peroxide, and about 4 weight-% octanoic acid. This compositioncan advantageously also include about 0.6 weight-% chelating agent. Thisconcentrate composition can be prepared according to the proportionsdescribed above. After combining the ingredients in these proportions,certain ingredients, such as the acetic acid, octanoic acid, andhydrogen peroxide, react to form peroxyacetic acid and peroxyoctanoicacid.

By about two weeks after combining, the reaction of these ingredientshas approached equilibrium. That is, the relative amounts of one or moreof peroxyacetic acid, acetic acid, peroxyoctanoic acid, octanoic acid,and hydrogen peroxide will be roughly constant. The equilibrium amountwill be affected by decomposition or other reaction, if any, of anylabile species. A preferred antimicrobial concentrate composition of thepresent invention includes an equilibrium mixture resulting from acombination of about 40 to about 70 weight-%, preferably about 45 toabout 65 weight-%, preferably about 50 to about 60 weight-% acetic acid;about 2 to about 20 weight-%, preferably about 2 to about 8 weight-%octanoic acid; and about 5 to about 15 weight-% hydrogen peroxide. Thisequilibrium composition can advantageously also include about 0.3 toabout 1 weight-% chelating agent. A more preferred antimicrobialconcentrate composition of the present invention includes an equilibriummixture resulting from a combination of about 55 weight-% acetic acid,about 11 weight-% hydrogen peroxide, and about 4 weight-% octanoic acid.This equilibrium composition can advantageously also include about 0.6weight-% chelating agent.

A preferred antimicrobial concentrate composition of the presentinvention includes about 30 to about 60 weight-%, preferably about 35 toabout 60 weight-%, preferably about 35 to about 50 weight-%, preferablyabout 40 to about 50 weight-% acetic acid; about 1 to about 15 weight-%,preferably about 1 to about 7 weight-% octanoic acid; about 2 to about12 weight-%, preferably about 2 to about 8 weight-% hydrogen peroxide;about 6 to about 16 weight-%, preferably about 8 to about 16 weight-%peroxyacetic acid; and about 0.1 to about 5 weight-%, preferably about0.1 to about 2 weight-% peroxyoctanoic acid. This concentratecomposition can advantageously also include about 0.1 to about 2weight-% chelating agent. Preferably, such an antimicrobial concentratecomposition includes about 40 weight-% acetic acid, about 3 weight-%octanoic acid, about 6 weight-% hydrogen peroxide, about 10 weight-%peroxyacetic acid, and about 0.8 weight-% peroxyoctanoic acid. Thisantimicrobial concentrate composition can advantageously include about0.6 weight-% chelating agent. Preferably, such an antimicrobialconcentrate composition includes about 41 weight-% acetic acid, about3.2 weight-% octanoic acid, about 6.2 weight-% hydrogen peroxide, about12 weight-% peroxyacetic acid, and about 0.80 weight-% peroxyoctanoicacid. This antimicrobial concentrate composition can advantageouslyinclude about 0.60 weight-% chelating agent. These preferredcompositions can be produced by mixing the acid and peroxide componentsat proportions listed in preceding paragraphs and allowing thecomposition to sit at ambient temperature for a period of about one toabout two weeks. That is, these preferred compositions can be consideredequilibrium compositions.

The compositions of the present invention also include antimicrobial usecompositions. Preferred antimicrobial use compositions include about 5to about 1000 ppm acetic acid; about 0.5 to about 100 ppm, preferablyabout 0.5 to about 75 ppm octanoic acid; about 1 to about 200 ppm,preferably about 1 to about 110 ppm hydrogen peroxide; about 2 to about300 ppm, preferably about 2 to about 220 ppm peroxyacetic acid, andabout 0.1 to about 20 ppm peroxyoctanoic acid. Such a use compositioncan advantageously include about 0.05 to about 30 ppm chelating agent.Preferably, such an antimicrobial use composition includes about 7(e.g., 6.8) ppm acetic acid, about 0.5 ppm octanoic acid, about 1 ppmhydrogen peroxide, about 2 ppm peroxyacetic acid, and about 0.1 ppmperoxyoctanoic acid. This use composition can advantageously includeabout 0.1 ppm chelating agent. Preferably, such an antimicrobial usecomposition includes about 20 (e.g. 17) ppm acetic acid, about 1 toabout 2 (e.g., 1.3) ppm octanoic acid, about 2 to about 3 (e.g., 2.6)ppm hydrogen peroxide, about 5 ppm peroxyacetic acid, and about 0.3 ppmperoxyoctanoic acid. This use composition can advantageously includeabout 0.3 ppm chelating agent. Preferably, such an antimicrobial usecomposition includes about 100 (e.g., 101) ppm acetic acid, about 8 ppmoctanoic acid, about 10 to about 20 (e.g., 16) ppm hydrogen peroxide,about 30 ppm peroxyacetic acid, and about 2 ppm peroxyoctanoic acid.This use composition can advantageously include about 1 to about 2 (e.g.1.5) ppm chelating agent. Preferably, such an antimicrobial usecomposition includes about 1000 (e.g. 985) ppm acetic acid, about 70 toabout 80 (e.g. 74) ppm octanoic acid, about 100 to about 200 (e.g. 110)ppm hydrogen peroxide, about 220 (e.g., 213) ppm peroxyacetic acid, andabout 10 to about 20 (e.g. 14) ppm peroxyoctanoic acid. This usecomposition can advantageously include about 10 to about 20 (e.g., 13)ppm chelating agent. Different dilutions of a concentrate compositioncan result in different levels of the components of the use composition,generally maintaining the relative proportions. For example, a usecomposition of the present invention can have concentrations twice, onehalf, or one quarter those listed above.

More About Liquid Peroxycarboxylic Acid Compositions

The level of reactive species, such as peroxy acids and/or hydrogenperoxide, in a use composition can be affected, typically diminished, byorganic matter that is found in or added to the use composition. Forexample, when the use composition is a bath or spray used for washingpoultry, poultry organic matter or accompanying organic matter willconsume peroxy acid and peroxide. Thus, the present amounts ofingredients in the use compositions refer to the composition before orearly in use, with the understanding that the amounts will diminish asorganic matter is added to the use composition.

In addition, the concentrate and use compositions change with age. It isbelieved that in approximately one year at ambient conditions the amountof peroxycarboxylic acid in the compositions can decrease to about 70%to about 80%, preferably about 80% to about 85%, of the initialequilibrium values or use composition levels. Such aged compositions areincluded in the scope of the present invention.

In each of the compositions described above, the chelating agent is anoptional, but preferred, ingredient. Typically the balance of each ofthe compositions described above is made up primarily or exclusively ofa solvent, such as water, e.g. tap or other potable water.

The compositions of the present invention preferably include onlyingredients that can be employed in poultry products or in poultry wash,handling, or processing, for example, according to government (e.g. FDAor USDA) rules and regulations. Preferably, the composition is free ofany peroxycarboxylic acid or carboxylic acid with 10, 12, or more carbonatoms. Such 10, 12, or more carbon acids can impart undesirable residues(e.g. bad tasting and/or malodorous) to poultry.

Each of the compositions listed above can be formulated by combiningeach of the listed ingredients. In addition, certain compositionsincluding both acid and peroxy acid can be formulated by combining theacids and hydrogen peroxide, which forms peroxy acids. Typically, the pHof an equilibrium mixture is less than about 1 or about 2, and the pH ofa 1% solution of the equilibrium mixture in water is about 2 to about 7,depending on the other components of the 1% solution, and the pH of ause composition can be from about 4 to about 7 depending on the othercomponents.

Other Fluid Compositions

The present methods can employ antimicrobial compositions including acritical, near critical, or supercritical (densified) fluid and anantimicrobial agent or a gaseous composition of an antimicrobial agent.The densified fluid can be a near critical, critical, supercriticalfluid, or another type of fluid with properties of a supercriticalfluid. Fluids suitable for densification include carbon dioxide, nitrousoxide, ammonia, xenon, krypton, methane, ethane, ethylene, propane,certain fluoroalkanes (e.g., chlorotrifluoromethane andmonofluoromethane), and the like, or mixtures thereof. Preferred fluidsinclude carbon dioxide. The antimicrobial composition can also includeother ingredients, such as another fluid or gas; a carrier, solvent orcosolvent; an oxidizing agent; a fatty acid; or a mixture thereof.

The antimicrobial agent applied with a densified fluid system can be anyof a variety of food surface compatible antimicrobial agents, such asone or more peroxycarboxylic acids, quaternary ammonium antimicrobialagents, acid sanitizers, mixtures thereof, and other food surfacecompatible antimicrobial agents. A preferred densified fluidantimicrobial composition that can be employed in the present methodsincludes densified carbon dioxide, peroxyacetic acid, hydrogen peroxide,acetic acid, peroxyoctanoic acid, and octanoic acid, which can bereferred to as a densified fluid mixed peroxycarboxylic acidcomposition.

In another embodiment, the antimicrobial composition includes the fluid,an antimicrobial agent, and any of the optional or added ingredients,but is in the form of a gas.

Densified fluid antimicrobial compositions can be applied by any ofseveral methods known to those of skill in the art. Such methods includeventing at the poultry carcass or part a vessel containing densifiedfluid and antimicrobial agent. The aqueous phase, which includeshydrogen peroxide, is advantageously retained in the device. The ventedgas includes an effective amount of antimicrobial agent making thedensified fluid peroxycarboxylic acid compositions effectiveantimicrobial agents.

Because of the high pressure nature of the densified fluid compositionsof the invention, these compositions are typically applied by venting avessel containing the composition through a pressure relief device thatis designed to promote rapid efficient coverage of the poultry carcassor part. Devices including such a pressure relief device includesprayers, foggers, foamers, foam pad applicators, brush applicators orany other device that can permit the expansion of the fluid materialsfrom high pressure to ambient pressure while applying the material tothe poultry carcass or part.

The densified fluid peroxycarboxylic acid composition can also beapplied to poultry by any of a variety of methods known for applyinggaseous agents to poultry during processing, including air chilling andpackaging (e.g. modified atmosphere packaging), particularly at stepswhere adding water to the poultry is disadvantageous. Other points inpoultry processing suitable for application of a gaseousperoxycarboxylic acid composition include any step including inertatmosphere processing, carbon dioxide stunning, and the like.

Densified fluid antimicrobial compositions can be made by reacting anoxidizable substrate with an oxidizing agent in a medium comprising adensified fluid to form an antimicrobial composition. This reaction istypically carried out in a vessel suitable for containing a densifiedfluid. Reacting can include adding to the vessel the oxidizablesubstrate and the oxidizing agent, and adding fluid to the vessel toform the densified fluid. A preferred reaction system involves areaction between a carboxylic acid and hydrogen peroxide to form thecorresponding peroxycarboxylic acid. The hydrogen peroxide is commonlysupplied in the form of an aqueous solution of hydrogen peroxide.Preferred carboxylic acids include acetic acid, heptanoic acid, octanoicacid, nonanoic acid, and mixtures thereof.

Supercritical, subcritical, near supercritical, and other dense fluidsand solvents that can be employed with such fluids are disclosed in U.S.Pat. No. 5,306,350, issued Apr. 26, 1994 to Hoy et al., which isincorporated herein for such disclosure. Supercritical and other denseforms of carbon dioxide, and cosolvents, co-surfactants, and otheradditives that can be employed with these forms of carbon dioxide aredisclosed in U.S. Pat. No. 5,866,005, issued Feb. 2, 1999 to DeSimone etal., which is incorporated herein for such disclosure.

Hydrogen Peroxide

The antimicrobial composition of the invention typically also include ahydrogen peroxide constituent. Hydrogen peroxide in combination with thepercarboxylic acid provides certain antimicrobial action againstmicroorganisms. Additionally, hydrogen peroxide can provide aneffervescent action which can irrigate any surface to which it isapplied. Hydrogen peroxide works with a mechanical flushing action onceapplied which further cleans the surface of application. An additionaladvantage of hydrogen peroxide is the food compatibility of thiscomposition upon use and decomposition. For example, combinations ofperoxyacetic acid, peroxyoctanoic acid, and hydrogen peroxide result inacetic acid, octanoic acid, water, and oxygen upon decomposition, all ofwhich are food product compatible.

Many oxidizing agents can be used for generating peroxycarboxylic acids.Suitable oxidizing agents, in addition to hydrogen peroxide, includeperborate, percarbonate, and persulfate. Hydrogen peroxide is generallypreferred for several reasons. After application of theH₂O₂/peroxycarboxylic acid germicidal agent, the residue left merelyincludes water and an acidic constituent. Deposition of these productson the surface of a poultry processing apparatus, such as a bath orspray apparatus, will not adversely effect the apparatus, the handlingor processing, or the poultry washed therein.

Hydrogen peroxide (H₂O₂), has a molecular weight of 34.014 and it is aweakly acidic, clear, colorless liquid. The four atoms are covalentlybonded in a H—O—O—H structure. Generally, hydrogen peroxide has amelting point of −0.41° C., a boiling point of 150.2° C., a density at25° C. of 1.4425 grams per cm³, and a viscosity of 1.245 centipoise at20° C.

Carrier

The composition of the invention also includes a carrier. The carrierprovides a medium which dissolves, suspends, or carries the othercomponents of the composition. For example, the carrier can provide amedium for solubilization and production of peroxycarboxylic acid andfor forming an equilibrium mixture. The carrier also functions todeliver and wet the antimicrobial composition of the invention to thepoultry. To this end, the carrier may contain any component orcomponents that can facilitate these functions.

Generally, the carrier includes primarily water which is an excellentsolubilizer and medium for reaction and equilibrium. The carrier caninclude or be primarily an organic solvent, such as simple alkylalcohols, e.g., ethanol, isopropanol, n-propanol, and the like. Polyolsare also useful carriers, including propylene glycol,polyethyleneglycol, glycerol, sorbitol, and the like. Any of thesecompounds may be used singly or in combination with other organic orinorganic constituents or, in combination with water or in mixturesthereof.

Generally, the carrier makes up a large portion of the composition ofthe invention and may be the balance of the composition apart from theactive antimicrobial components, adjuvants, and the like. Here again,the carrier concentration and type will depend upon the nature of thecomposition as a whole, the environmental storage, and method ofapplication including concentration of the antimicrobial agent, amongother factors. Notably the carrier should be chosen and used at aconcentration which does not inhibit the antimicrobial efficacy of theactive agent in the composition of the invention.

Adjuvants

The antimicrobial composition of the invention can also include anynumber of adjuvants. Specifically, the composition of the invention caninclude stabilizing agents, wetting agents, hydrotropes, thickeners, asurfactant, foaming agents, acidifiers, as well as pigments or dyesamong any number of constituents which can be added to the composition.Such adjuvants can be preformulated with the antimicrobial compositionof the invention or added to the system simultaneously, or even after,the addition of the antimicrobial composition. The composition of theinvention can also contain any number of other constituents asnecessitated by the application, which are known to those of skill inthe art and which can facilitate the activity of the present invention.

Stabilizing Agents

Stabilizing agents can be added to the composition of the invention, forexample, to stabilize the peracid and hydrogen peroxide and prevent thepremature oxidation of this constituent within the composition of theinvention.

Chelating agents or sequestrants generally useful as stabilizing agentsin the present compositions include alkyl diamine polyacetic acid-typechelating agents such as EDTA (ethylene diamine tetraacetate tetrasodiumsalt), acrylic and polyacrylic acid-type stabilizing agents, phosphonicacid, and phosphonate-type chelating agents among others. Preferablesequestrants include phosphonic acids and phosphonate salts including1-hydroxy ethyldene-1,1-diphosphonic acid (CH₃C(PO₃H₂)₂OH) (HEDP),amino[tri(methylene phosphonic acid)] ([CH₂PO₃H₂]₂(ethylenediamine[tetra methylene-phosphonic acid)], 2-phosphenebutane-1,2,4-tricarboxylic acid, as well as the alkyl metal salts,ammonium salts, or alkyloyl amine salts, such as mono, di, ortetra-ethanolamine salts. The stabilizing agent is used in aconcentration ranging from about 0 weight percent to about 20 weightpercent of the composition, preferably from about 0.1 weight percent toabout 10 weight percent of the composition, and most preferably fromabout 0.2 weight percent to 5 weight percent of the composition.

Amino phosphates and phosphonates are also suitable for use as chelatingagents in the compositions of the invention and include ethylene diamine(tetramethylene phosphonates), nitrilotrismethylene phosphates,diethylenetriamine (pentamethylene phosphonates). These aminophosphonates commonly contain alkyl or alkaline groups with less than 8carbon atoms. The phosphonic acid may also include a low molecularweight phosphonopolycarboxylic acid such as one having about 2-4carboxylic acid moieties and about 1-3 phosphonic acid groups. Suchacids include 1-phosphono-1-methylsuccinic acid, phosphonosuccinic acidand 2-phosphonobutane-1,2,4-tricarboxylic acid.

Commercially available food additive chelating agents includephosphonates sold under the trade name DEQUEST® including, for example,1-hydroxyethylidene-1,1-diphosphonic acid, available from MonsantoIndustrial Chemicals Co., St. Louis, Mo., as DEQUEST®2010;amino(tri(methylenephosphonic acid)), (N[CH₂PO₃H₂]₃), available fromMonsanto as DEQUEST® 2000; ethylenediamine[tetra(methylenephosphonicacid)] available from Monsanto as DEQUEST® 2041; and2-phosphonobutane-1,2,4-tricarboxylic acid available from Mobay ChemicalCorporation, Inorganic Chemicals Division, Pittsburgh, Pa., as BayhibitAM.

The above-mentioned phosphonic acids can also be used in the form ofwater soluble acid salts, particularly the alkali metal salts, such assodium or potassium; the ammonium salts or the alkylol amine salts wherethe alkylol has 2 to 3 carbon atoms, such as mono-, di-, ortriethanolamine salts. If desired, mixtures of the individual phosphonicacids or their acid salts can also be used.

The concentration of chelating agent useful in the present inventiongenerally ranges from about 0.01 to about 10 wt-%, preferably from about0.1 to about 5 wt-%, most preferably from about 0.5 to about 2 wt-%.

Wetting or Defoaming Agents

Also useful in the composition of the invention are wetting anddefoaming agents. Wetting agents function to increase the surfacecontact or penetration activity of the antimicrobial composition of theinvention. Wetting agents which can be used in the composition of theinvention include any of those constituents known within the art toraise the surface activity of the composition of the invention.

Along these lines, surfactants, and especially nonionic surfactants, canalso be useful in the present invention. Nonionic surfactants which canbe useful in the present invention are those which include ethyleneoxide moieties, propylene oxide moieties, as well a mixtures thereof,and ethylene oxide-propylene oxide moieties in either heteric or blockformation. Additionally useful in the present invention are nonionicsurfactants which include an alkyl ethylene oxide compounds, alkylpropylene oxide compounds, as well as mixtures thereof, and alkylethylene oxide-propylene oxide compounds where the ethylene oxidepropylene oxide moiety is either in heteric or block formation. Furtheruseful in the present invention are nonionic surfactants having anymixture or combination of ethylene oxide-propylene oxide moieties linkedto a alkyl chain where the ethylene oxide and propylene oxide moietiescan be in any randomized or ordered pattern and of any specific length.Nonionic surfactants useful in the present invention can also includerandomized sections of block and heteric ethylene oxide propylene oxide,or ethylene oxide-propylene oxide, such as ethylene diamine ethyleneoxides, ethylene diamine propylene oxides, mixtures thereof, andethylene diamine EO-PO compounds, including those sold under thetradename Tetronic.

Generally, the concentration of nonionic surfactant used in acomposition of the present invention can range from about 0 wt-% toabout 5 wt-% of the composition, preferably from about 0 wt-% to about 2wt-% of the concentrate composition, and most preferably from about 0wt-% to about 1 wt-% of the composition.

The composition used in the methods of the invention can also containadditional ingredients as necessary to assist in defoaming.

Generally, defoamers which can be used in accordance with the inventioninclude silica and silicones; aliphatic acids or esters; alcohols;sulfates or sulfonates; amines or amides; halogenated compounds such asfluorochlorohydrocarbons; vegetable oils, waxes, mineral oils as well astheir sulfated derivatives; fatty acid soaps such as alkali, alkalineearth metal soaps; and phosphates and phosphate esters such as alkyl andalkaline diphosphates, and tributyl phosphates among others; andmixtures thereof.

Especially preferable, are those antifoaming agents or defoamers whichare of food grade quality given the application of the method of theinvention. To this end, one of the more effective antifoaming agentsincludes silicones. Silicones such as dimethyl silicone, glycolpolysiloxane, methylphenol polysiloxane, trialkyl or tetralkyl silanes,hydrophobic silica defoamers and mixtures thereof can all be used indefoaming applications. Commercial defoamers commonly available includesilicones such as Ardefoam® from Armour Industrial Chemical Companywhich is a silicone bound in an organic emulsion; Foam Kill® or Kresseo®available from Krusable Chemical Company which are silicone andnon-silicone type defoamers as well as silicone esters; and Anti-Foam A®and DC-200 from Dow Corning Corporation which are both food grade typesilicones among others. These defoamers can be present at aconcentration range from about 0.01 wt-% to 5 wt-%, preferably fromabout 0.01 wt-% to 2 wt-%, and most preferably from about 0.01 wt-% toabout 1 wt-%.

Hydrotrope

The poultry wash composition of the invention or employed in the methodsof the invention may also include a hydrotrope coupler or solubilizer.Such materials can be used to ensure that the composition remains phasestable and in a single highly active aqueous form. Such hydrotropesolubilizers or couplers can be used at compositions which maintainphase stability but do not result in unwanted compositional interaction.

Representative classes of hydrotrope solubilizers or coupling agentsinclude an anionic surfactant such as an alkyl sulfate, an alkyl oralkane sulfonate, a linear alkyl benzene or naphthalene sulfonate, asecondary alkane sulfonate, alkyl ether sulfate or sulfonate, an alkylphosphate or phosphonate, dialkyl sulfosuccinic acid ester, sugar esters(e.g., sorbitan esters) and a C₈₋₁₀ alkyl glucoside.

Preferred coupling agents for use in the rinse agents of the inventioninclude n-octane sulfonate and aromatic sulfonates such as an alkyl arylsulfonate (e.g., sodium xylene sulfonate or naphthalene sulfonate). Manyhydrotrope solubilizers independently exhibit some degree ofantimicrobial activity at low pH. Such action adds to the efficacy ofthe invention but is not a primary criterion used in selecting anappropriate solubilizing agent. Since the presence of theperoxycarboxylic acid material in the protonated neutral state providesbeneficial biocidal or antimicrobial activity, the coupling agent shouldbe selected not for its independent antimicrobial activity but for itsability to provide effective single phase composition stability in thepresence of substantially insoluble peroxycarboxylic acid materials andthe more soluble compositions of the invention. Generally, any number ofsurfactants may be used consistent with the purpose of this constituent.

Anionic surfactants useful with the invention include alkylcarboxylates, linear alkylbenzene sulfonates, paraffin sulfonates andsecondary n-alkane sulfonates, sulfosuccinate esters and sulfated linearalcohols.

Zwitterionic or amphoteric surfactants useful with the invention includeβ-N-alkylaminopropionic acids, n-alkyl-β-iminodipropionic acids,imidazoline carboxylates, n-alky-Iletaines, amine oxides, sulfobetainesand sultaines.

Nonionic surfactants useful in the context of this invention aregenerally polyether (also known as polyalkylene oxide, polyoxyalkyleneor polyalkylene glycol) compounds. More particularly, the polyethercompounds are generally polyoxypropylene or polyoxyethylene glycolcompounds. Typically, the surfactants useful in the context of thisinvention are synthetic organic polyoxypropylene (PO)-polyoxyethylene(EO) block copolymers. These surfactants have a diblock polymerincluding an EO block and a PO block, a center block of polyoxypropyleneunits (PO), and having blocks of polyoxyethylene grated onto thepolyoxypropylene unit or a center block of EO with attached PO blocks.Further, this surfactant can have further blocks of eitherpolyoxyethylene or polyoxypropylene in the molecule. The averagemolecular weight of useful surfactants ranges from about 1000 to about40,000 and the weight percent content of ethylene oxide ranges fromabout 10-80% by weight.

Also useful in the context of this invention are surfactants includingalcohol alkoxylates having EO, PO and BO blocks. Straight chain primaryaliphatic alcohol alkoxylates can be particularly useful as sheetingagents. Such alkoxylates are also available from several sourcesincluding BASF Wyandotte where they are known as “Plurafac” surfactants.A particular group of alcohol alkoxylates found to be useful are thosehaving the general formula R-(EO)_(m)—(PO)_(n) wherein m is an integerof about 2-10 and n is an integer from about 2-20. R can be any suitableradical such as a straight chain alkyl group having from about 6-20carbon atoms.

Other useful nonionic surfactants of the invention include cappedaliphatic alcohol alkoxylates. These end caps include but are notlimited to methyl, ethyl, propyl, butyl, benzyl and chlorine. Usefulalcohol alkoxylated include ethylene diamine ethylene oxides, ethylenediamine propylene oxides, mixtures thereof, and ethylene diamine EO-POcompounds, including those sold under the tradename Tetronic.Preferably, such surfactants have a molecular weight of about 400 to10,000. Capping improves the compatibility between the nonionic and theoxidizers hydrogen peroxide and peroxycarboxylic acid, when formulatedinto a single composition. Other useful nonionic surfactants arealkylpolyglycosides.

Another useful nonionic surfactant of the invention is a fatty acidalkoxylate wherein the surfactant includes a fatty acid moiety with anester group including a block of EO, a block of PO or a mixed block orheteric group. The molecular weights of such surfactants range fromabout 400 to about 10,000, a preferred surfactant has an EO content ofabout 30 to 50 wt-% and wherein the fatty acid moiety contains fromabout 8 to about 18 carbon atoms.

Similarly, alkyl phenol alkoxylates have also been found useful in theinvention. Such surfactants can be made from an alkyl phenol moietyhaving an alkyl group with 4 to about 18 carbon atoms, can contain anethylene oxide block, a propylene oxide block or a mixed ethylene oxide,propylene oxide block or heteric polymer moiety. Preferably suchsurfactants have a molecular weight of about 400 to about 10,000 andhave from about 5 to about 20 units of ethylene oxide, propylene oxideor mixtures thereof.

The concentration of hydrotrope useful in the present inventiongenerally ranges from about 0.1 to about 20 wt-%, preferably from about0.5 to about 10 wt-%, most preferably from about 1 to about 4 wt-%.

Thickening or Gelling Agents

Thickeners useful in the present invention include those which do notleave contaminating residue on the surface of poultry or poultryprocessing apparatus. That is, preferred thickeners or gelling agents donot include components incompatible with food or other sensitiveproducts in contact areas.

Generally, thickeners which may be used in the present invention includenatural gums such as xanthan gum, guar gum, or other gums from plantmucilage; polysaccharide based thickeners, such as alginates, starches,and cellulosic polymers (e.g., carboxymethyl cellulose); polyacrylatesthickeners; and hydrocolloid thickeners, such as pectin. Generally, theconcentration of thickener employed in the present compositions ormethods will be dictated by the desired viscosity within the finalcomposition. However, as a general guideline, the viscosity of thickenerwithin the present composition ranges from about 0.1 wt-% to about 1.5wt-%, preferably from about 0.1 wt-% to about 1.0 wt-%, and mostpreferably from about 0.1 wt-% to about 0.5 wt-%.

Formulation

The compositions of or used in the methods of the invention can beformulated by combining the antimicrobially active materials (e.g.,carboxylic acids, peroxycarboxylic acids, and hydrogen peroxide) withadjuvant or other components with the materials that form theantimicrobial composition. The compositions can also be formulated withpreformed peroxycarboxylic acids. The preferred compositions of theinvention can be made by mixing the carboxylic acid or mixture thereofwith an optional hydrotrope solubilizer or coupler, reacting the mixturewith hydrogen peroxide and then adding the balance of requiredingredients to provide rinsing and antimicrobial action.

A stable equilibrium mixture is produced containing the carboxylic acidor blend with hydrogen peroxide and allowing the mixture to stand for1-14 days at 15° C. or more. With this preparatory method, anequilibrium mixture will be formed containing an amount of hydrogenperoxide, unoxidized acid, oxidized or peroxycarboxylic acid andunmodified couplers, solubilizer, or stabilizers.

Use Compositions

The invention contemplates a concentrate composition which is diluted toa use solution prior to application to poultry. Primarily for reasons ofeconomics, the concentrate would normally be marketed and an end userwould preferably dilute the concentrate with water or an aqueous diluentto a use solution.

The level of active components in the concentrate composition isdependent on the intended dilution factor and the desired activity ofthe peroxycarboxylic acid compound and the carboxylic acid. Generally, adilution of about 0.5 to about 20 fluid ounces to about 100 gallons ofwater is used for aqueous antimicrobial compositions. Higher usedilutions can be employed if elevated use temperature (greater than 25°C.) or extended exposure time (greater than 30 seconds) can be employed.In the typical use locus, the concentrate is diluted with a majorproportion of water and used for poultry processing using commonlyavailable tap or service water mixing the materials at a dilution ratioof about 3 to about 20 ounces of concentrate per 100 gallons of water.

Methods Employing Mixed Peroxycarboxylic Acid Compositions

Poultry Processing

The concentrate and use compositions of the present invention can beemployed for a variety of antimicrobial purposes, preferably as or forforming water-based systems for processing and/or washing poultry. Thepresent compositions and methods can be employed for processing poultryand/or poultry meat at any step from gathering the live birds throughpackaging the final product. For example, the present compositions andmethods can employed for washing, rinsing, chilling, or scalding poultrycarcasses, poultry carcass parts, or poultry organs for reducingcontamination of these items with spoilage/decay-causing bacteria, andpathogenic bacteria.

Before processing, live poultry are generally transported to andgathered at the beginning of a processing line. Poultry can be washedbefore entering the processing line. Processing typically begins withsacrificing the bird, typically by electrical stunning, followed by neckcutting and bleeding. A first washing step, known as scalding (e.g.submersion or immersion scalding) typically follows bleeding and loosensattachment of feathers to poultry skin. Submersion scalding can beaccomplished according to the methods and employing compositions of thepresent invention. Submersion scalding typically includes immersing astunned and bled bird into a scalding hot bath of water or a liquidantimicrobial composition, typically at a temperature of about 50 toabout 80° C., preferably about 50 to about 60° C. The liquidantimicrobial composition in the bath can be agitated, sonicated, orpumped to increase contact of the composition with the carcass. Scaldingis generally conducted in a scald tank or trough, which contains thescalding liquid with sufficient liquid depth to completely submerse thepoultry carcass. The carcass is generally transported through the tankor trough by conveyor at a speed that provides a few minutes in thescalding liquid.

According to the present invention, the scalding bath can include amixed peroxycarboxylic acid antimicrobial composition, preferably acomposition of the present invention. Preferably, the scalding hot bathcontains a peroxycarboxylic acid antimicrobial composition with about 2to about 50 ppm, preferably about 30 ppm of peroxycarboxylic acidpresent as a mixture of peroxyacetic acid and peroxyoctanoic acid, andamounts and additional ingredients as described herein. The scaldingbath can also include one or more of the additional ingredientspermitted in scalding baths.

After submersion scalding, the poultry is typically picked and,optionally, singed before the next washing process. This second washingprocess is generally known as “dress” rinsing, “New York dress” rinsing,or post-pick rinsing, which rinses residual feathers and follicleresidues from the carcass. Dress rinsing typically includes spraying apicked carcass with water, typically at a temperature of about 5 toabout 30° C. To increase contact with the carcass, the antimicrobialcompositions in the spray water can be applied at higher pressures, flowrates, temperatures, or with agitation or ultrasonic energy. Dressrinsing is typically accomplished with a washing apparatus such as awash or spray cabinet with stationary or moving spray nozzles.Alternatively, a “flood”-rinsing or liquid submersion washing apparatusmay be used immediately after picking.

According to the present invention, dress rinsing can be accomplishedemploying a peroxycarboxylic acid antimicrobial composition, preferablya composition of the present invention. For example, the dress rinsingcan employ a peroxycarboxylic acid antimicrobial composition with about50 to about 300 ppm, preferably about 200 ppm of peroxycarboxylic acidpresent as a mixture of peroxyacetic acid and peroxyoctanoic acid, andamounts and additional ingredients as described herein.

Dress rinsing is typically a final washing step before dismembering thepoultry. Dismembering can include removing the head, the feet,eviscerating, and removing the neck, in any order commonly employed inpoultry processing. The dismembered and eviscerated poultry can then besubjected to a washing step known as inside-outside bird washing (IOBW).Inside-outside bird washing washes the interior (body cavity) andexterior of the bird. Inside-outside bird washing typically includesrinsing the interior and exterior surfaces of the carcass with streamsor floods of water, typically at a temperature of about 5 to about 30°C. To increase contact with the carcass, the antimicrobial compositionsin the spray water can be applied at higher pressures, flow rates,temperatures, or with agitation or ultrasonic energy. Inside-outsidebird washing is generally accomplished by an apparatus that floods thebird carcass with streams of water in the inner cavity and over theexterior of the carcass. Such an apparatus can include a series of fixedspray nozzles to apply antimicrobial composition to the exterior of thebird and a rinse probe or bayonet that enters and applies antimicrobialcomposition to the body cavity.

According to the present invention, inside-outside bird washing can beaccomplished employing a peroxycarboxylic acid antimicrobialcomposition, preferably a composition of the present invention. Forexample, inside-outside bird washing can employ a peroxycarboxylic acidantimicrobial composition about 20 to about 200 ppm preferably about 50to about 100 ppm of peroxycarboxylic acid present as a mixture ofperoxyacetic acid and peroxyoctanoic acid, and amounts and additionalingredients as described herein.

After inside-outside bird washing, both the interior and the exterior ofthe bird can be subjected to further decontamination. This furtherdecontamination can be accomplished in part by a step commonly known asantimicrobial spray rinsing, sanitizing rinsing, or finishing rinsing.Such rinsing typically includes spraying the interior and exteriorsurfaces of the carcass with water, typically at a temperature of about5 to about 30° C. To increase contact with the carcass, theantimicrobial compositions in the spray water can be applied using fixedor articulating nozzles, at higher pressures, flow rates, temperatures,with agitation or ultrasonic energy, or with rotary brushes. Sprayrinsing is typically accomplished by an apparatus such as a spraycabinet with stationary or moving spray nozzles. The nozzles create amist, vapor, or spray that contacts the carcass surfaces.

According to the present invention, antimicrobial spray rinsing,sanitizing rinsing, or finishing rinsing can be accomplished employing aperoxycarboxylic acid antimicrobial composition, preferably acomposition of the present invention. For example, spray rinsing canemploy a peroxycarboxylic acid antimicrobial composition with about 50to about 300 ppm preferably about 100 to about 200 ppm ofperoxycarboxylic acid present as a mixture of peroxyacetic acid andperoxyoctanoic acid, and amounts and additional ingredients as describedherein.

After spray rinsing, the bird can be made ready for packaging or forfurther processing by chilling, specifically submersion chilling or airchilling. Submersion chilling both washes and cools the bird to retainquality of the meat. Submersion chilling typically includes submersingthe carcass completely in water or slush, typically at a temperature ofless than about 5° C., until the temperature of the carcass approachesthat of the water or slush. Chilling of the carcass can be accomplishedby submersion in a single bath, or in two or more stages, each of alower temperature. Water can be applied with agitation or ultrasonicenergy to increase contact with the carcass. Submersion chilling istypically accomplished by an apparatus such as a tank containing thechilling liquid with sufficient liquid depth to completely submerse thepoultry carcass. The carcass can be conveyed through the chiller byvarious mechanisms, such as an auger feed or a drag bottom conveyor.Submersion chilling can also be accomplished by tumbling the carcass ina chilled water cascade.

According to the present invention, submersion chilling can beaccomplished employing a peroxycarboxylic acid antimicrobialcomposition, preferably a composition of the present invention. Forexample, submersion chilling can employ a peroxycarboxylic acidantimicrobial composition with about 2 to about 100 ppm preferably about2 to about 30 ppm of peroxycarboxylic acid present as a mixture ofperoxyacetic acid and peroxyoctanoic acid, and amounts and additionalingredients as described herein.

Like submersion chilling, air chilling or cryogenic chilling cools thebird to retain quality of the meat. Air cooling can be less effectivefor decontaminating the bird, as the air typically would not dissolve,suspend, or wash away contaminants. Air chilling with a gas including anantimicrobial agent can, however, reduce the burden of microbial, andother, contaminants on the bird. Air chilling typically includesenclosing the carcass in a chamber having a temperature below about 5°C. until the carcass is chilled. Air chilling can be accomplished byapplying a cryogenic fluid or gas as a blanket or spray.

According to the present invention, air chilling can be accomplishedemploying a peroxycarboxylic acid antimicrobial composition, preferablya composition of the present invention. For example, air chillingcompositions can include a gaseous or densified fluid antimicrobialcomposition.

After chilling, the bird can be subjected to additional processing stepsincluding weighing, quality grading, allocation, portioning, deboning,and the like. This further processing can also include methods orcompositions according to the present invention for washing with mixedperoxycarboxylic acid compositions. For example, it can be advantageousto wash poultry portions, such as legs, breast quarters, wings, and thelike, formed by portioning the bird. Such portioning forms or revealsnew meat, skin, or bone surfaces which may be subject to contaminationand benefit from treatment with an antimicrobial composition. Similarly,deboning a poultry carcass or a portion of a poultry carcass can exposeadditional areas of the meat or bone to microbial contamination. Washingthe deboned poultry carcass or portion with a mixed peroxycarboxylicacid composition can advantageously reduce any such contamination. Inaddition, during any further processing, the deboned meat can also comeinto contact with microbes, for example, on contaminated surfaces.Washing the deboned meat with a mixed peroxycarboxylic acid compositioncan reduce such contamination. Washing can be accomplished by spraying,immersing, tumbling, or a combination thereof, or by applying a gaseousor densified fluid antimicrobial composition.

Usable side products of poultry include heart, liver, and gizzard (e.g.giblets), neck, and the like. These are typically harvested later inprocessing, and are sold as food products. Of course, microbialcontamination of such food products is undesirable. Thus, these sideproducts can also be washed with a mixed peroxycarboxylic acidcomposition in methods of the present invention. Typically, these sideproducts will be washed after harvesting from the poultry carcass andbefore packaging. They can be washed by submersion or spraying, ortransported in a flume including the antimicrobial composition. They canbe contacted with an antimicrobial composition according to theinvention in a giblet chiller or ice chiller.

The poultry, poultry product, poultry portion, poultry side product, orthe like can be packaged before sending it to more processing, toanother processor, into commerce, or to the consumer. Any such poultrycan be washed with a water based mixed peroxycarboxylic acidantimicrobial composition, which can then be removed (e.g., drained,blown, or blotted) from the poultry. In certain circumstances wettingthe poultry before packaging is disadvantageous. In such circumstances,a gaseous or densified fluid form of the peroxycarboxylic acidantimicrobial composition can be employed for reducing the microbialburden on the poultry. Such a gaseous composition can be employed in avariety of processes known for exposing poultry to a gas before orduring packaging, such as modified atmosphere packaging.

The advantageous stability of mixed peroxycarboxylic acid compositionsin such methods, which include the presence of poultry debris orresidue, makes these compositions competitive with cheaper, less stable,and potentially toxic chlorinated compounds. Preferred methods of thepresent invention include agitation or sonication of the usecomposition, particularly as a concentrate is added to water to make theuse composition. Preferred methods include water systems that have someagitation, spraying, or other mixing of the solution. The poultryproduct can be contacted with the compositions of the inventioneffective to result in a reduction significantly greater than isachieved by washing with water, or at least a 50% reduction, preferablyat least a 90% reduction, preferably at least a 99% reduction in theresident microbial preparation.

The present methods require a certain minimal contact time of thecomposition with poultry for occurrence of significant antimicrobialeffect. The contact time can vary with concentration of the usecomposition, method of applying the use composition, temperature of theuse composition, amount of soil on the poultry, number of microorganismson the poultry, or the like. Preferably the exposure time is at leastabout 5 to about 15 seconds.

Spraying Poultry

A preferred method for washing poultry employs a pressure spray of themixed peroxycarboxylic acid composition. During application of the spraysolution on the poultry product, the surface of the poultry product canbe moved with mechanical action, preferably agitated, rubbed, brushed,etc. Agitation can be by physical scrubbing of the poultry product,through the action of the spray solution under pressure, throughsonication, or by other methods. Agitation increases the efficacy of thespray solution in killing micro-organisms, perhaps due to betterexposure of the solution into the crevasses or small colonies containingthe micro-organisms. The spray solution, before application, can also beheated to a temperature of about 15 to 20° C., preferably about 20 to60° C. to increase efficacy.

Application of the material by spray can be accomplished using a manualspray wand application, an automatic spray of poultry product movingalong a production line using multiple spray heads to ensure completecontact or other spray means. One preferred automatic spray applicationinvolves the use of a spray booth. The spray booth substantiallyconfines the sprayed composition to within the parameter of the booth.The production line moves the poultry product through the entryway intothe spray booth in which the poultry product is sprayed on all itsexterior surfaces with sprays within the booth. After a completecoverage of the material and drainage of the material from the poultryproduct within the booth, the poultry product can then exit the booth ina fully treated form. The spray booth can include steam jets that can beused to apply the antimicrobial compositions of the invention. Thesesteam jets can be used in combination with cooling water to ensure thatthe treatment reaching the poultry product surface is less than 65° C.,preferably less than 60° C. The temperature of the spray on the poultryproduct is important to ensure that the poultry product is notsubstantially altered (cooked) by the temperature of the spray. Thespray pattern can be virtually any useful spray pattern.

Immersing Poultry

During processing of the poultry product, the poultry product can beimmersed into a tank containing a quantity of washing solution. Thewashing solution is preferably agitated to increase the efficacy of thesolution and the speed in which the solution reduces micro-organismsaccompanying to the poultry product. Agitation can be obtained byconventional methods, including ultrasonics, aeration by bubbling airthrough the solution, by mechanical methods, such as strainers, paddles,brushes, pump driven liquid jets, or by combinations of these methods.The washing solution can be heated to increase the efficacy of thesolution in killing micro-organisms. It is preferable that the poultryproduct be immersed in the washing solution after the poultry producthave been eviscerated and before any cooling process such as a chillertank or a chill water spray.

Foam Treating Poultry

In another alternative embodiment of the present invention, the poultryproduct can be treated with a foaming version of the composition. Thefoam can be prepared by mixing foaming surfactants with the washingsolution at time of use. The foaming surfactants can be nonionic,anionic or cationic in nature. Examples of useful surfactant typesinclude, but are not limited to the following: alcohol ethoxylates,alcohol ethoxylate carboxylate, amine oxides, alkyl sulfates, alkylether sulfate, sulfonates, quaternary ammonium compounds, alkylsarcosines, betaines and alkyl amides. The foaming surfactant istypically mixed at time of use with the washing solution. Use solutionlevels of the foaming agents is from about 50 ppm to about 2.0 wt-%. Attime of use, compressed air can be injected into the mixture, thenapplied to the poultry product surface through a foam application devicesuch as a tank foamer or an aspirated wall mounted roamer.

Gel Treating Poultry

In another alternative embodiment of the present invention, the poultryproduct can be treated with a thickened or gelled version of thecomposition. In the thickened or gelled state the washing solutionremains in contact with the poultry product surface for longer periodsof time, thus increasing the antimicrobial efficacy. The thickened orgelled solution will also adhere to vertical surfaces. The compositionor the washing solution can be thickened or gelled using existingtechnologies such as: xanthan gum, polymeric thickeners, cellulosethickeners or the like. Rod micelle forming systems such as amine oxidesand anionic counter ions could also be used. The thickeners or gelforming agents can be used either in the concentrated product or mixingwith the washing solution, at time of use. Typical use levels ofthickeners or gel agents range from about 100 ppm to about 10 wt-%.

Light Treating Poultry

In another alternative embodiment of the present invention, the poultryproduct can be exposed to an activating light (or other electromagneticradiation) source following application of the washing solution. Theactivating light (or other electromagnetic radiation) can improve theantimicrobial efficacy of the washing solution. The light can beultraviolet light, infrared light, visible light, or a combinationthereof. Other forms of electromagnetic radiation include radar andmicrowave.

Processing Poultry Wash Water

Washing poultry can employ a large volume of water, or another carrier.Poultry wash water can be used more than once (recycled), provided thewater can be treated so that it does not transfer undesirable microbesto the poultry being washed with the recycled wash water. One way toprevent the transfer of such undesirable microbes, is to reduce themicrobial burden of the recycled wash water by adding a mixture ofperoxycarboxylic acids. For example, if the fluid to be recycled iswater-based and lacking any peroxycarboxylic acid, a mixedperoxycarboxylic acid concentrate composition can be added to result inan effective antimicrobial concentration of peroxycarboxylic acid in thefluid to be recycled. Alternatively, if the fluid to be recycled alreadyincludes or has included a peroxycarboxylic acid, a mixedperoxycarboxylic acid concentrate composition can be added to increaseany concentration of peroxycarboxylic acid to an effective antimicrobiallevel. It may be that the peroxycarboxylic acid in the solution to berecycled has been totally depleted, in which case more of the mixedperoxycarboxylic acid composition is added.

In some circumstances, the water to be recycled includes a substantialburden of organic matter or microbes. If this is the case, the water maybe unsuitable for recycling. However, if the water is to be recycled,the operator adds a sufficient quantity of the mixed peroxycarboxylicacid composition to provide an effective antimicrobial amount of theperoxycarboxylic acid after a certain amount is consumed by the organicburden or microbes already present. Then, the recycled fluid can be usedwith antimicrobial effect. Routine testing can be employed fordetermining levels of peroxycarboxylic acid, or of organic burden.

In each case, the method of recycling the poultry wash water includesrecovering the poultry wash water, adding a mixed composition ofperoxycarboxylic acids, and reusing the poultry wash water for washingpoultry, for example, as described above. The poultry wash water can berecovered from steps in poultry processing including submersionscalding, dress rinsing, inside-outside bird washing, spray rinsing, andsubmersion chilling. Methods of recovering wash water from these stepsare well-known to those skilled in the poultry washing and/or processingarts. The wash water can also be strained, filtered, diluted, orotherwise cleaned in processed during recycling.

The present invention may be better understood with reference to thefollowing examples. These examples are intended to be representative ofspecific embodiments of the invention, and are not intended as limitingthe scope of the invention.

EXAMPLES Example 1 Formulas for Peroxyacetic/Peroxyoctanoic AcidMixtures Having Activity Against Microbes Contaminating Poultry

A preferred antimicrobial concentrate composition of the invention wasformulated as:

Material Weight - % Glacial Acetic Acid 55 Hydrogen Peroxide 11 HEDP 0.6Octanoic Acid 4

The remainder of this concentrate composition was water.

This concentrate formulation converted to a composition including peroxyacids during storage for two weeks at generally ambient conditions. Inthis case, the concentrate composition converted to:

Typical Weight Percent of Chemical In Chemical Concentrate 2 WeeksPost-Manufacture Acetic Acid 41 Hydrogen Peroxide 6.2 HEDP 0.6 OctanoicAcid 3.2 Peroxyacetic Acid 12 Peroxyoctanoic Acid 0.8

The remainder of this concentrate composition was water.

Such concentrate compositions were diluted to form use compositions ofthe present invention, which include:

Use Use Use Use Solution 1 Solution 2 Solution 3 Solution 4 Component(ppm) (ppm) (ppm) (ppm) Glacial Acetic 6.8 17 101 985 Acid DeionizedBalance Balance Balance Balance water Peroxyacetic 2 5 30 213 Acid HEDP0.1 0.3 1.5 13 Octanoic Acid 0.5 1.3 8 74 Peroxyoctanoic 0.1 0.3 2 14Acid Hydrogen 1.0 2.6 16 110 Peroxide

Example 2 Spray Application of a Mixed Peroxycarboxylic AcidAntimicrobial Composition Reduces Bacterial Pathogen Contamination onPoultry

Spray application of an antimicrobial composition of the invention wastested and shown to significantly reduce bacterial pathogencontamination on poultry carcass samples.

Materials and Methods

Carcass samples were contaminated with either Salmonella typhimuriumATCC 13311, Escherichia coli serotype O157:H7 ATCC 43895, or Listeriamonocytogenes (Petite Scott A) ATCC 49594. Identities of these bacteriawere confirmed based on gram stain reactions, microscopic morphology andgrowth characteristics using the appropriate selective medium. Thesestrains were grown in culture, by conventional techniques, and adjustedto yield≧10⁷ colony forming units per milliliter (CFU/mL).

Carcass samples were prepared by inoculating the exterior of a thawed2×2 inch square of chicken skin with 1 mL of a pathogen culture. Thesquare of skin was depressed to form a bowl, and the culture was allowedto sit in this bowl for 5 min to allow attachment of the bacteria. Afterattachment, culture was removed from the skin sample and each sample wasplaced on a metal stand, epidermal side/inoculated side up.

The skin sample was then sprayed with an antimicrobial compositiondescribed in Example 1. For use, the composition was diluted to 200±10ppm total peroxyacid measured as peroxyacetic acid. The poultry carcasssample was sprayed with the composition for 15 seconds at 60 psi androom temperature.

After spraying, the skin samples were aseptically removed and placedinto 20 mL of solution including an agent that inactivates theperoxycarboxylic acids without killing bacteria. The remaining bacteriawere suspended by vortexing and serial dilutions of this solution wereplated for growth of the bacteria. Dilutions were prepared usingphosphate buffered dilution water (PBDW). S. typhimurium and L.monocytogenes plates were incubated at 37° C. for 48 hours. E. coliO157:H7 plates were incubated at 37° C. for 24 hours. For each sample,the number of colony forming units per skin square were calculated.

Results

Statistical analysis of the numbers of bacteria on skin samplesdemonstrated that spray application of the antimicrobial composition ofthe invention significantly reduced levels of Salmonella typhimurium,Escherichia coli, and Listeria monocytogenes. These results areillustrated in Table 1 below.

TABLE 1 Log Reduction of Bacteria Levels After Spraying With a MixedPeroxycarboxylic Acid Antimicrobial Agent Peroxycarboxylic Acid BacteriaAntimicrobial Agent Salmonella typhimurium 0.8 Escherichia coli 3.2Listeria monocytogenes 2.1

Conclusion

Spray application of an antimicrobial composition of the inventionsignificantly reduces bacterial pathogen contamination on poultrycarcass samples.

Example 3 Submersion Application of a Mixed Peroxycarboxylic AcidAntimicrobial Composition Reduces Bacterial Pathogen Contamination onPoultry

Submersion application of an antimicrobial composition of the inventionwas tested and shown to significantly reduce bacterial pathogencontamination on poultry carcass samples.

Materials and Methods

Bacteria were selected and cultured generally as described in Example 2above, except that the bacteria were diluted to ≧10⁶ colony formingunits per milliliter (CFU/mL) for inoculation of carcass samples.

Carcass samples were prepared by thawing frozen chicken wings andlivers. The thawed samples were inoculated by submersing in thesuspension of bacteria. Other surfaces were not inoculated. Theinoculated surface was marked for identification and allowed to drainand sit for 5 min. at room temperature.

The antimicrobial composition was as described in Example 1. The usesolution was diluted to 30 ppm total peroxyacid measured as peroxyaceticacid. Antimicrobial agent was applied by submersing the inoculated anduninoculated surfaces for 60 min in the same 2 liters of a use solutionof the antimicrobial agent at 4° C. The same experiment was performedusing water without the antimicrobial agent.

After submersing for 60 min., the inoculated and uninoculated surfaceswere removed from the antimicrobial agent use solution or water andgently agitated in 100 mL of solution including an agent thatinactivates the peroxycarboxylic acids without killing bacteria.Removing and analyzing the uninoculated surfaces was necessary tomeasure cross contamination of bacteria from the inoculated surfaces.Serial dilutions of this solution were plated for growth of the bacteriaas described above in Example 2. Cross contamination log reduction wascalculated by subtracting the Log number of bacteria on uninoculatedsurfaces submersed in the antimicrobial use solution from the Log numberof surviving bacteria on uninoculated surfaces submersed in water.

Results

Statistical analysis of the numbers of bacteria on carcass samplesdemonstrated that submersion application of the antimicrobialcomposition of the invention significantly reduced levels of Salmonellatyphimurium, Escherichia coli, and Listeria monocytogenes. These resultsare illustrated in Tables 2 and 3 below.

TABLE 2 Log Reduction of Bacteria Levels After Submersing a Chicken Wingin a Mixed Peroxycarboxylic Acid Antimicrobial Agent PeroxycarboxylicAcid Bacteria Antimicrobial Agent Salmonella typhimurium 0.3 Escherichiacoli 1.2 Listeria monocytogenes 1.3

TABLE 3 Log Reduction of Bacteria Levels After Submersing a ChickenLiver in a Mixed Peroxycarboxylic Acid Antimicrobial AgentPeroxycarboxylic Acid Bacteria Antimicrobial Agent Salmonellatyphimurium 0.5 Escherichia coli 0.9 Listeria monocytogenes 0.6

Conclusion

Submersion application of an antimicrobial composition of the inventionsignificantly reduces bacterial pathogen contamination on poultrycarcass samples.

Example 4 Reduction of Spoilage or Decay Causing Bacteria on PoultryCarcasses

This study determined that a mixed peroxycarboxylic acid antimicrobialcomposition in water used for spraying or submersing eviscerated chickencarcasses provided a reduction of total aerobic bacteria, coliformbacteria, and Escherichia coli.

Materials and Methods

Freshly collected chicken carcasses were subjected to spraying with orsubmersion in an antimicrobial composition described in Example 1 above.Use solutions, spray time and pressure, and submersion temperature andduration were as described in Examples 2 and 3 above. Some carcasseswere both sprayed and submersed. Control carcasses were untreated.

Each carcass was then placed in a collection bag using freshly glovedhands. In the bag, the carcass was rinsed with Butterfield's PhosphateDiluent (BPD) and the BPD solution collected for microbiology testing.Known, standard procedures for quantifying total aerobic bacteria,coliform bacteria, and Escherichia coli were employed.

Results

Statistical analysis of the numbers of bacteria on carcass samplesdemonstrated that spray, submersion, and combination application of theantimicrobial composition of the invention significantly reduced levelsof total aerobic bacteria, coliform bacteria, and Escherichia coli.These results are illustrated in Table 4 below.

TABLE 4 Log Reduction of Bacteria Levels After Treating a ChickenCarcass with a Mixed Peroxycarboxylic Acid Antimicrobial AgentApplication Aerobic Plate Count E. coil Count Coliform Count Spray 0.620.84 0.64 Submersion 1.21 1.37 1.27 Spray and 1.33 1.44 1.31 Submersion

Conclusion

Spray, submersion, and spray and submersion application of anantimicrobial composition of the invention significantly reducescontamination by spoilage or decay causing bacteria on poultrycarcasses.

It should be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the content clearly dictates otherwise. Thus, for example,reference to a composition containing “a compound” includes a mixture oftwo or more compounds. It should also be noted that the term “or” isgenerally employed in its sense including “and/or” unless the contentclearly dictates otherwise.

All publications and patent applications in this specification areindicative of the level of ordinary skill in the art to which thisinvention pertains.

The invention has been described with reference to various specific andpreferred embodiments and techniques. However, it should be understoodthat many variations and modifications may be made while remainingwithin the spirit and scope of the invention.

We claim:
 1. A method of reducing a microbial population on poultryduring processing comprising: applying to the poultry during processinga mixed peroxycarboxylic acid antimicrobial composition in an amount andtime sufficient to reduce the microbial population; recovering theapplied mixed peroxycarboxylic acid antimicrobial composition; andadding to the recovered composition a sufficient amount of a mixture ofperoxycarboxylic acids to yield a recycled mixed peroxycarboxylic acidantimicrobial composition.
 2. The method of claim 1, wherein the poultrybeing processed comprises chicken, turkey, ostrich, game hen, squab,guinea fowl, pheasant, duck, goose, or emu.
 3. The method of claim 1,comprising applying the mixed peroxycarboxylic acid composition bysubmersing the poultry.
 4. The method of claim 3, comprising applyingthe mixed peroxycarboxylic acid composition by submersion scalding, bysubmersion chilling, by hydro-cooling or chilling, tumble immersion, orby a combination thereof.
 5. The method of claim 3, comprising applyingthe mixed peroxycarboxylic acid composition for a duration and at aconcentration selected to yield visually imperceptible darkening ofsubcutaneous bruises, pooled blood, or a combination thereof.
 6. Themethod of claim 1, comprising applying the mixed peroxycarboxylic acidcomposition by rinsing or spraying the poultry.
 7. The method of claim6, comprising applying the mixed peroxycarboxylic acid composition witha de-feathering picker, by inside-outside bird washing, by dressrinsing, by spray rinsing, or a combination thereof.
 8. The method ofclaim 1, comprising applying the mixed peroxycarboxylic acid compositionto a whole poultry carcass.
 9. The method of claim 8, comprisingapplying the mixed peroxycarboxylic acid composition to a poultrycarcass that has been subjected to stunning, bleeding, scalding,picking, singeing, or a combination thereof.
 10. The method of claim 1,comprising applying the mixed peroxycarboxylic acid composition to oneor more dismembered parts of a poultry carcass.
 11. The method of claim10, comprising applying the mixed peroxycarboxylic acid composition to apoultry carcass that has been subjected to beheading, removing feet,eviscerating, neck-cropping, portioning, or a combination thereof. 12.The method of claim 11, comprising applying the mixed peroxycarboxylicacid composition to a poultry leg, thigh, breast quarter, wing, orcombination thereof of a poultry that has been subjected to portioning.13. The method of claim 10, comprising applying the mixedperoxycarboxylic acid composition to a poultry that has also beensubjected to boning.
 14. The method of claim 13, comprising applying themixed peroxycarboxylic acid composition to a boned poultry leg, thigh,breast, wing, or combination thereof.
 15. The method of claim 1,comprising applying the mixed peroxycarboxylic acid composition by airchilling.
 16. The method of claim 1, further comprising exposing thepoultry to activated light.
 17. The method of claim 16, wherein theactivated light comprises ultraviolet light, infrared light, visiblelight, or a combination thereof.
 18. The method of claim 1, wherein themixed peroxycarboxylic acid antimicrobial composition comprises: atleast about 2 ppm of one or more mono- or di-peroxycarboxylic acidshaving up to 6 carbon atoms; and at least 0.5 ppm of one or morecarboxylic acids having up to 12 carbon atoms.
 19. The method of claim18, wherein the mixed peroxycarboxylic acid composition comprises one ormore peroxycarboxylic acids having from 2 to 6 carbon atoms and aperoxycarboxylic acid having from 7 to 12 carbon atoms.
 20. The methodof claim 19, wherein the mixed peroxycarboxylic acid compositioncomprises peroxyacetic acid and peroxyoctanoic acid.
 21. The method ofclaim 20, wherein the mixed peroxycarboxylic acid antimicrobialcomposition further comprises stabilizing agent, wetting agent,hydrotrope, thickener, foaming agent, acidifier, pigment, dye,surfactant, or a combination thereof.
 22. The method of claim 1, whereinthe microbial population is the result of contamination by fecal matteror digestive tract content.
 23. The method of claim 22, wherein themicrobial population is reduced in a continuous online process.
 24. Themethod of claim 1, further comprising applying the recycled compositionto poultry during processing.
 25. The method of claim 1, wherein themixture of peroxycarboxylic acids comprises peroxyacetic acid andperoxyoctanoic acid.
 26. The method of claim 25, wherein the mixture ofperoxycarboxylic acids comprises about 30 to about 60 weight-% aceticacid, about 1 to about 15 weight-% octanoic acid, about 2 to about 12weight-% hydrogen peroxide, about 6 to about 16 weight-% peroxyaceticacid, and about 0.1 to about 5 weight -% peroxyoctanoic acid, and about0.1 to about 2 weight-% chelating agent.
 27. The method of claim 1,wherein the recycled mixed peroxycarboxylic acid antimicrobialcomposition comprises: at least about 2 ppm of one or more mono- ordi-peroxycarboxylic acids having up to 6 carbon atoms; and at least 0.5ppm of one or more carboxylic acids having up to 12 carbon atoms. 28.The method of claim 27, wherein the recycled mixed peroxycarboxylic acidcomposition comprises one or more peroxycarboxylic acids having from 2to 6 carbon atoms and a peroxycarboxylic acid having from 7 to 12 carbonatoms.
 29. The method of claim 1, further comprising diluting anantimicrobial concentrate composition to yield the mixedperoxycarboxylic acid antimicrobial composition.
 30. The method of claim29, wherein the antimicrobial concentrate composition comprises: about30 to about 60 weight-% acetic acid; about 1 to about 15 weight-%octanoic acid; about 2 to about 12 weight-% hydrogen peroxide; about 6to about 16 weight-% peroxyacetic acid; about 0.1 to about 5 weight-%peroxyoctanoic acid; and about 0.1 to about 2 weight-% chelating agent.31. The method of claim 30, wherein the antimicrobial concentratecomposition further comprises stabilizing agent, wetting agent.hydrotrope, thickener, foaming agent, acidifier, pigment, dye,surfactant, or a combination thereof.
 32. The method of claim 30,wherein the antimicrobial concentrate composition comprises: about 40weight-% acetic acid; about 3 weight-% octanoic acid; about 6 weight-%hydrogen peroxide; about 10 weight-% peroxyacetic acid; about 0.8weight-% peroxyoctanoic acid; and about 0.6 weight-% chelating agent.33. The method of claim 29, wherein the antimicrobial concentratecomposition comprises: an equilibrium mixture resulting from acomposition comprising: about 40 to about 70 weight-% acetic acid; about2 to about 20 weight-% octanoic acid. about 5 to about 15 weight-%hydrogen peroxide; and about 0.3 to about 1 weight-% chelating agent.34. The method of claim 33, wherein the antimicrobial concentratecomposition comprises: an equilibrium mixture resulting from acomposition comprising: about 55 weight-% acetic acid; about 11 weight-%hydrogen peroxide; about 0.6 weight-% chelating agent; and about 4weight-% octanoic acid.
 35. The method of claim 33, wherein theantimicrobial concentrate composition further comprises stabilizingagent, wetting agent, hydrotrope, thickener, foaming agent, acidifier,pigment, dye, surfactant, or a combination thereof.
 36. The method ofclaim 1, wherein the mixed peroxycarboxylic acid antimicrobialcomposition comprises: about 5 to about 1000 ppm acetic acid; about 0.5to about 100 ppm octanoic acid; about 1 to about 200 ppm hydrogenperoxide; about 2 to about 300 ppm peroxyacetic acid; about 0.1 to about20 ppm peroxyoctanoic acid; and about 3 to about 30 ppm chelating agent.37. The method of claim 36, wherein the mixed peroxycarboxylic acidantimicrobial compostion further comprises stabilizing agent, wettingagent, hydrotrope, thickener, foaming agent, acidifier, pigment, dye,surfactant, or a combination thereof.
 38. A method of reducing amicrobial population on poultry during processing comprising:sacrificing the poultry; removing feathers from the sacrificed poultry;removing head, feet, neck, or more than one of head, neck, and feet fromthe defeathered poultry; eviscerating the defeathered poultry;inside-outside bird washing the eviscerated poultry; spraying theinside-outside bird washed poultry with a mixed peroxycarboxylic acidantimicrobial composition in an amount and time sufficient to reduce themicrobial population; chilling the peroxycarboxylic acid treatedpoultry.
 39. The method of claim 38, wherein the microbial population isthe result of contamination by fecal matter or digestive tract content.40. The method of claim 39, wherein the microbial population is reducedin a continuous online process.
 41. The method of claim 38, whereinchilling comprises submersing the poultry in a chilled mixedperoxycarboxylic acid composition.
 42. A method of reducing a microbialpopulation on poultry during processing comprising submersing thepoultry in a chilled mixed peroxycarboxylic acid composition.